DENSO First Time Fit spark plug wire sets feature a factory fit and appearance. They come pre-assembled and ready to install right out of the box. Denso wires can handle temperatures from 40° to 428° Fahrenheit. Boots and end caps are designed to "click" reassuring a quality fitment and connection even in tight and hard to reach locations. Denso wire sets meet the requirements of SAE's strict J2031 Class E standards which insure a quality, long lasting product.